Thanx Miles
For years I had a sneeky feeling that that's what was happening with me with Rs & RWs.
But just for the record, in desperation to fix my seemingly busted drives DesktopXP after using some DVD-R:-
"Sony 1x-16x compatible 4.7 / 120min DVD Recordable / Enregistrable"
I downloaded the free InCD 6.6.5.100 & lo & behold it formated those unusable before DVD-Rs & you drag into them files which become instantly readable, without the need to "write these files", & also they delete instantly just like the floppys do.
I am flabergasted after so much trouble I went to with that staff.
How long they will last is another matter. ..........nick